@@ -15,6 +15,7 @@
#include <sys/time.h>
#include <fcntl.h>
+#include "vm_util.h"
#include "../kselftest.h"
/*
@@ -159,6 +160,9 @@ static int validate_complete_va_space(void)
if (prot[0] != 'r')
continue;
+ if (check_vmflag_io((void *)start_addr))
+ continue;
+
/*
* Confirm whether MAP_CHUNK_SIZE chunk can be found or not.
* If write succeeds, no need to check MAP_CHUNK_SIZE - 1
@@ -400,3 +400,24 @@ unsigned long get_free_hugepages(void)
fclose(f);
return fhp;
}
+
+bool check_vmflag_io(void *addr)
+{
+ char *saveptr, *flag, *strtok_arg;
+ char buffer[MAX_LINE_LENGTH];
+
+ strtok_arg = __get_smap_entry(addr, "VmFlags:", buffer, sizeof(buffer));
+ if (!strtok_arg)
+ ksft_exit_fail_msg("%s: No VmFlags for %p\n", __func__, addr);
+
+ while (true) {
+ flag = strtok_r(strtok_arg, " ", &saveptr);
+ if (!flag)
+ break;
+ if (strcmp(flag, "io") == 0)
+ return true;
+ strtok_arg = NULL;
+ }
+
+ return false;
+}
@@ -53,6 +53,7 @@ int uffd_unregister(int uffd, void *addr, uint64_t len);
int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
bool miss, bool wp, bool minor, uint64_t *ioctls);
unsigned long get_free_hugepages(void);
+bool check_vmflag_io(void *addr);
/*
* On ppc64 this will only work with radix 2M hugepage size
The virtual_address_range selftest reads from the start of each mapping listed in /proc/self/maps. However not all mappings are valid to be arbitrarily accessed. For example the vvar data used for virtual clocks on x86 [vvar_vclock] can only be accessed if 1) the kernel configuration enables virtual clocks and 2) the hypervisor provided the data for it. Only the VDSO itself has the necessary information to know this. Since commit e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") the virtual clock data was split out into its own mapping, leading to EFAULT from read() during the validation. Check for the VM_IO flag as a proxy. It is present for the VVAR mappings and MMIO ranges can be dangerous to access arbitrarily. Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202412271148.2656e485-lkp@intel.com Fixes: e93d2521b27f ("x86/vdso: Split virtual clock pages into dedicated mapping") Fixes: 010409649885 ("selftests/mm: confirm VA exhaustion without reliance on correctness of mmap()") Suggested-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/lkml/e97c2a5d-c815-4936-a767-ac42a3220a90@redhat.com/ Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Revert "selftests/mm: virtual_address_range: Avoid reading VVAR mappings" This reverts commit 05cc5d292ac4238684b59922aecf59c932edefa0. --- tools/testing/selftests/mm/virtual_address_range.c | 4 ++++ tools/testing/selftests/mm/vm_util.c | 21 +++++++++++++++++++++ tools/testing/selftests/mm/vm_util.h | 1 + 3 files changed, 26 insertions(+)